1. Field of the Invention
The present invention relates to an audio processor which converts an inputted digital audio data into an analog audio data.
2. Description of the Related Art
Conventionally, an audio processor which converts an inputted digital audio data into an analog audio data converts the digital audio data into the analog audio data at a sampling frequency of the digital audio data (a sampling frequency when converting the digital audio data from the analog audio data into the digital audio data). That is to say, when the digital audio data is inputted, such an audio processor firstly adjusts the sampling frequency to convert the digital audio data into the analog audio data to be same as the sampling frequency of the inputted digital audio data, and subsequently converts the inputted digital audio data into the analog audio data at the adjusted sampling frequency. The converted analog audio data is outputted to a speaker, and the speaker reproduces an audio based on the inputted digital audio data.
When a sampling frequency of a digital audio data which is earlier inputted is different from that of a digital audio data which is subsequently inputted, the above audio processor carries out a mute processing so as not to output the analog audio data which is converted from the digital audio data until the adjustment of the sampling frequency is completed. As a result, a sound interrupt (the audio is not reproduced) often occurs at the beginning of the audio to be reproduced (the audio based on the subsequently inputted digital audio data) due to the mute processing.
There is a known audio processor which avoids the sound interrupt at the beginning of the audio (refer to Japanese Laid-Open Patent Publication No. 2007-80347, for example). When the sampling frequencies of the successive digital audio data are different from each other, the audio processor (digital amplifier) described in the above publication No. 2007-80347 avoids the sound interrupt at the beginning of the audio (the audio based on the subsequent digital audio data) by converting the subsequent digital audio data into the analog audio data after waiting a time for adjusting the sampling frequency.
Meanwhile, there is a known broadcasting receiver for receiving a radio broadcasting which outputs an audio of an analog broadcasting, which has the same contents as a digital broadcasting, while a setting of a signal processing unit is changed when the sampling frequency of the digital broadcasting is changed (refer to Japanese Laid-Open Patent Publication No. 2005-277791, for example). Moreover, among receiving apparatuses which records audio data received from network in a buffer and reads out the audio data recorded in the buffer in accordance with a reference clock, there is a known receiving apparatus which clears an audio data recorded in the buffer when the sampling frequency of the audio data is changed (refer to Japanese Laid-Open Patent Publication No. 2002-344561, for example). Moreover, there is a known reproducing apparatus for reproducing a digital audio data which prevents a noise generation which occurs when switching a mode of reproduction (refer to Japanese Laid-Open Patent Publication No. 2001-143394, for example).
However, in the above audio processor described in the publication No. 2007-80347, the inputted digital audio data is converted into the analog audio data after waiting the time for adjusting the sampling frequency, so that the processing of the digital audio data becomes complex. Besides, even when applying the contents disclosed in the above publication Nos. 2005-277791, 2002-344561, and 2001-143394, the above problem cannot be resolved.